Study On Influence Of Surface Characteristics Of Medical Needle On Puncture Process

With the rapid development of modern medical technology,minimally invasive surgery and localized treatment are gradually adopted in clinical medicine to simplify surgery and ensure safety.Minimally invasive surgery involves a wide range of procedures,including needle biopsy sampling,local brachytherapy,local drug delivery and robot-assisted puncture technology.Puncture biopsy is the main method to obtain tumor tissue samples in bone and soft tissue for pathological diagnosis.The main tool for the implementation of puncture surgery is puncture needle.The interaction between needle and tissue in puncture process is complex.The needle and tissue deformation and force in puncture process are affected by different biological tissues,puncture needle and puncture parameters.If the surface morphology of needle changes,it will cause the interaction between needle and tissue then affect the effect of puncture operation.In this paper,the surface of medical puncture needle is treated in different ways to obtain different surface characteristics.Through the finite element simulation model of biological soft tissue puncture and in vitro experiment,the changes of puncture force,tissue and needle deformation during puncture process of puncture needle with different surface characteristics were explored.It is of great significance to study the interface characteristics between biological tissues and puncture needle and to develop new medical puncture needle.Firstly,a puncture simulation model was established and verified by in vitro puncture experiment.Due to the complex characteristics of biological soft tissue,the Mooney-Rivlin model of constitutive equation suitable for biological soft tissue should be selected according to the uniaxial tensile test data.Moreover,a geometric model of puncture needle with the same shape and material parameters as a puncture needle used in the in vitro puncture experiment was established.At the same time,the contact between needle and tissue,mesh and boundary conditions were set.Then the platform of in vitro puncture experiment was established and the appropriate sample materials were selected for the experiment.The accuracy of the simulation model was verified by comparing the data obtained by simulation model with the in vitro experiment.Secondly,coating was applied to the surface of needle to investigate the influence of surface coating on puncture process.A suitable medical coating was selected and applied on the surface of puncture needle.The model of coated needle was established and the surface friction coefficient of coated needle was measured by experiment.In vitro puncture experiment was carried out with conventional and coated needle.Combined with the results of experiment and simulation,the difference of puncture process using coated needle and conventional needle was analyzed.The results show that using coating can significantly reduce the friction and soft tissue damage in puncture process.It is show that the application of coating can optimize the tissue fiber adhesion on needle surface and ruduce the puncture force and effectively prevent puncture needle deflection.Thirdly,a surface microtexture was designed to alleviate tissue adhesion during the puncture process.Laser technology was used to carve micro-texture on the surface of puncture needle.Then the puncture process of needles with different specifications of micro-texture was analyzed.The changes of puncture force,needle deflection and tissue adhesion during process using needle with micro-texture were analyzed by in vitro puncture experiment.According to the experimental results,it can be concluded that the existence of microtexture can effectively reduce the tissue adhesion on needle surface and the needle deflection during puncture process.At the same time,puncture force of needle was obviously reduced.Finally,the results of in vitro puncture experiment using needle with microtexture and coated needle were compared to compare the intensity of influence appling different puncture needle surface characteristics on the puncture process.The application of coating has a more significant positive effect on reducing puncture force and its effect of reducing the adhesion of tissue debris is better than that of surface microtexture.However,coating was as effective as microtexture in increasing the tendency of debris to leave needle surface.Because the coating and microtexture did not change the diameter of needle,the needle body would not have large deflection on the basis of reducing the puncture force.More than this,they can weaken the deflection of needle body,which further ensured that the puncture needle could accurately reach the target tissue in the process of puncture.